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Full text of "Practical Organic Chemistry"

APPENDIX

249

W.   Wislicenus  and   others, of which   the  following  examples

must suffice ;                                                                     «!

•

;,ITn ~ QJ Ir,CO.CIL,COOCJir>

Arctic rsirr.              -HvmmyUmnxoii: -estcfP      -f C0HP)OH.

K'OOCJlr,  I   CI !....('( K><\,1 1,,       .-  ILCCU'IUCOOCoIlr,

|M,niii<:<-st.-r.              Acvlir CSKT.                     l'Wmyl:u:«:tic ester.     " -| 'C

Gjiir,oH.
- (:.,iiri(xx).c().cii.,.cx)oc,iir,

1 I:,.( '< X )G,I Ir,        <>x.'ilylaa>ti<: estc-r.        "-|-  C,l 1^011.
AtK-tiiM-stcr.'

From this it would appear that condensation might always be.
effected between an ester on the one hand and a compound
containing the group CIL.CO on the other. This seems very
generally to be the rase, and Claisen has succeeded in pro-
ducing condensation products between esters and ketones or
aldehydes containing this group. (See Prep. 100, p. 212.)

The formula for ethyl aeetoacetatc would imply the properties
of a ketone, a view which is borne out.by its reduction to a
hydroxy-acid,

cii:,.c:iion.(:iTa.cooc,jTB,

/3-Hycln>xyl»utyri<: ester.

and by its behaviour with phenylhydra/.ine and hydroxylamine.
The latter reactions give rise to the formation of the usual
phenylhydraxone and oximc, whilst a molecule of alcohol is also
removed resulting in a closed chain, in the former case phenyl-
methylpynizolone, and in the latter methylisoxazolone being"
formed,

CII.{.CCIIo.CO

I                                             ' II    " I

N-------O

Phriiylnifthylpyr.'i/olune.                    Methylisoxa/olone.

The "mcthylcnc" group (CH2) standing between two CO
groups, such as occurs in acetoacetic ester, is characterised by
certain properties, which are shared by all compounds of similar
structure, vi/., by their behaviour towards nitrous acid, diazo-
benxcne salts, and metallic sodium or sodium alcoholate.

The first reaction leads to the formation of isonitrosoacetone,

cn.,.co.cii,,.cooa,irB + UNO., = CII.,.CO.CTT:NOII + co.,
+ CoII5OII.